The utility model discloses a maintenance platform of straight king -post of detachable cable -stay bridge, it is including suspending operation platform in midair, dismantled and assembled platform and hoist engine system, it includes the two sets of semiorbicular platform that hangs that centers on the king -post and build to suspend operation platform in midair, dismantled and assembled platform comprises a plurality of layers of platform, every layer of platform is formed by two sections detachable linkage segment butt joints, every section linkage segment is rather than adjacent hanging with the round pin hub connection between the platform, when the linkage segment is in the butt joint state, it forms closed ring shape around the king -post to hang platform and dismantled and assembled platform, the hoist engine system constitutes with shaped steel and the pulley guider who installs at the king -post top at the hoist engine of cable -stay bridge bridge floor by installing, the wire rope of hoist engine walks around pulley guider and the wire rope who hangs the platform hang hole suspension connection. The utility model discloses an examine and repair the platform and when running into barrier such as suspension cable, can dismantle the platform and the cut -through thing through dismantling it, especially be suitable for and carry out checksum maintenance operations to cable -stay bridge cable system.